Centralized music transmission system



Juez-1,1949.

Filed NOV. 25, 1946 s Ki LAcKol-F f CENTRALIZED MUSIC TRANSMISSION SYSTEM 5 Sheets-Sheet l VH' f L13 je /ar azi/1f( Pff/naz @Y June 21, 1949.

s. K.; LAcKoFF CENTRALIZED MUSIC TRANSMSSON SYSTEM Filed NOV. 25, 1946 5 Sheets-Sheet 2 ATTORNEY Junezl, 1949. S..K.| AKOFF .2,474,110

CENTRALIZED MUSIC TRANSMISSION SYSTEM MWI' mi #Il ATTORNEY June 21, 1949. i s. K.V LAcKoFF' 2,474,110

CENTRALIZED MUSIC TRANSMISSION SYSTEM Filed Nov. 25, 1946 5 SheetsQSheet 4 `lune 21, 1949. s. K. L AcKoFF 2,474,110

GENTRALIZED MUSIC TRANSMISSION SYSTEM Filed Nov. 25, 1946 5 sheets-sheet 5 4 i l i l l i 70.4. C, Hlm

INVENTOR ATTORNEY Patented June 21, 1949 CENTRALIZED MUSICS TRANSIVII'SSION SYSTEM Samuel K. Lackoff, Astoria, N. Y., assignor to Telomatic Products, Inc., Passaic, N. J., a corporationsof New Jersey ApplicationNovember 25, 1946, Serial No. 712,217

Claims.

l'. The. present invention relates to music reproduction systemsand'more particularly to a central-ized music system wherein music of several 4.types is reproduced automatically a-nd trans.-

mitted to variousr subscribers Vwithout the necessity off-operators being in constant. attendance. Atpresent. several,y distinct types ofv systems are well known inthe art. tor the reproduction of music, they most common, perhaps being that of wired music, wherein' local coin-controlled subscriber stationsare provided with a record index, and uponthe selection. of a desired record the patron-deposits a coin which connects; the local station with a studio. A studio operator then vocally asks for vthey request which has been selected and' the patron Vocally answers, after which the selected record is-placed upon a studio record player with thereproducedmusic being tranmitted backsto the localstation. This particular type of vsystem requires an extensive array of record. players' at the studio: depending .upon the` number ofesubscribers. In addition to the initial equipment investment which is necessari-ly very substantial the operating costs are exceedingly:highfbecause of the requirement for trainedy and arduous studio personnel in order to promptly respond to request callsy from the local--stations. Moreover, since telephone lines are employed which extend through the telephone-eXchangef-rom the local stations to the studio. the toll charges for rental` of the telephone 4lin-es constitute a largefpercentageof operating costs. l

Another type. systemis the well known juke box type wherein a plurality of records are placedy in a record player atalocal establishment and by depositing coins either directly inthe player or at rlocal remotey stations a selected record isplayed. While this particular type lof system is perhaps thefmost economical. from the standpoint of initial cost` and maintenance, its disadvantage resides in-the fact-thatthe number of musical selections are quite limited and the Vmusic isv confined entirely to the establishment in which the equipment is installed.

A further type'` systemkis: that.r wherein a prearranged,program*istransmittedto a local sub.- scribcr or group of Isubscribers at certain preselected hours of thedays directly from a centrall studio. This type offsystem is usually rented torestaurants: on a monthly rate basis but, like the-.wired music: system, requires azcentral studio. In `many' instances therequirement. for a large investment in centrali station equipment isa v`dotlrn-nent.'because the lnumber `,of possible sub?- scribers is hardly sufficient to justify such installation and the required operators, especially in towns ofy smallpopulation.

It is accordingly the primary object of the present invention to provide a centralized music system which requires a minimum of equipment and which is entirely automatic in its operation so as to eliminate the necessity-for operators being in attendance andY wherein the reproduced music may originate either in a local studio provided the proprietor elects 4to acquire the necessary automatic record changers, or the music maybe rented from an existing. studio and transmitted over telephone lines to a distribution console located in a small town not justifying theexpense of local-studio automatic record changers.

Another object ofthe present invention is the provision of a centralized music system wherein only one studio ampliiier is required for two types of music which will service substantially any number of subscribers.

Another object of the present invention is the provision of a centralized music system wherein the appropriate type music is automatically selected vand transmitted tothe desired group of subscribers.

Another object of the present invention is the provision of. a centralized music. system wherein three types of music isv selectively transmitted over two main line channels to subscribers.

Another object of the present invention is the provision of a centralized music system wherein the required equipment is reduced to a minimum by the utilization of butone studio amplifier for eachr type ofV music and no distribution panelis required with the system' automatically compensating for variations in load.

Another object ofv the present invention is the provision. of a. centralized music system which operates entirely automatically once the system is set for a twenty-four hour period and the amplitude of the music. is maintained constant by an automa-tic tone-levelv equalizer.

Another object ci the presentA invention is the provision or. a centralized music systemr wherein 'they maintenance thereof is reduced-to a minimum and the necessity for highly skilled help is eliminated by the utilization ofplug-in containers having 'mounted therein all parts norm-ally subject to'wearxsothat they may be readily 'removed'and replaced with the same ease as atube is removed andi replaced.

A.. furtherobjfect` oiy the presentJ invention-is the provision .of a centralized music system 3 wherein all of the distribution equipment is housed within a unit console containing two high-fidelity ampliers for furnishing three programs over two telephone channels, an emergency amplifier for automatically and instantaneously taking over the program should either of the channel amplifiers fail, a turntable for dedication programs and an automatic selector.

A further object of the present invention is the provision of a centralized music system wherein three types of music are distributed over two telephone line channels with the local amplifiers at each subscriber location being synchronized with the distribution amplifier so that the local subscriber receives only the type of music desired and for which he has subscribed.

Still further objects of the present invention will become obvious to those skilled in the art by reference to the accompanying drawings wherein:

Figure 1 is a block diagram illustration of the centralized music reproduction system of the present invention from the studio to the subscribers local stations,

Figure 2 is a schematic illustration of the studio portion of the centralized music system of the present invention,

Figure 3 is a circuit diagram of the automatic selector portion of the distribution console which forms part of the studio equipment,

Figure 4 is a circuit diagram of the turn-table and studio amplifier for one transmission channel which forms still other units of the distribution console,

Figure 5 is a circuit diagram of the studio amplifier for a second transmission channel together with an emergency stand-by amplifier which forms the remaining units of the distribution console,

Figure 6 is a circuit diagram of the various elements of the circuits which are subject to Wear and require occasional replacement, and

Figure 7 is perspective view of the plug-in container unit housing the various elements such as shown in Figure 6.

Referring now to the drawings in detail the system as shown in Figure 1 comprises a distribution console 5, the uppermost unit of which is an automatic selector 6 for selecting the proper automatic record changer 1 at the appropriate time, through connecting control cables 8 with the automatic record changer 'I being in a studio at the site of the distribution console, or in a remote studio from which the transmitted music is rented. Immediately below the selector 6 is a turn-table unit 9 which is utilized for dedication programs only, as hereinafter pointed out, and an announcement can be made at any time from a microphone I detachably connected to the console 5, and which is selectively connected to the desired channel by a hand switch I I.

The remaining units of the console consist of three amplifiers, with one such amplifier I2 constituting the one for selectively amplifying factory type and restaurant type music while arnplifier I3 is employed in connection with the transmission of hit-parade or measured music. The remaining or lowermost amplifier I4 is an emergency stand-by which automatically becomes operative at any instant that either amplifier I2 or I3 becomes defective. Suitable input cables I5 extend from the automatic record changer 1 to the distribution console 5 so that the music from the appropriate records passes through the proper amplifier before transmission 4 over telephone line channel #I and channel #2 coaxial cables, to the telephone exchange central station I6.

The various subscriber lines I1 extend from the local amplifiers I8 to the telephone exchange IB Where they are connected to the proper distribution panel for the subscribed music of channel #I or #2. Although there is substantially no limitation to the number of subscribers or customers for any type of music, only one for each type has been shown. For example, in Figure l there is shown a local factory amplifier I8 which comprises, in addition to the customary amplifying circuit and speaker, a 24 hour electric clock I9 receiving 110 volt A. C. power at the subscribers location, which in turn operates a cam 20 engageable with a switch 22 for automatically turning the local factory amplifier I8 on and off during alternate fifteen minute periods of each of the twenty-four hours, except when no music is desired by the amplifier being turned off by a manually operated local switch or at the studio.

Since factory amplifier I8 is connected to channel #I, music will be received during the quarter hour period that distribution amplifier I2 receives factory type music from the automatic record changers 1. Moreover, as will be hereinafter pointed out, the automatic selector 6 is provided with an electric clock which is synchronized with the local amplifier clocks I9 so that the latter operates simultaneously with the selector clock for the preselected type of music. It will also be noted from Figure 1 that local restaurant amplifier I8 is also identical in construction to the factory amplifier I8, the only difference being in the setting of the cams 20, so that during any quarter hour period when one amplifier is on the other is off Accordingly, when distribution amplifier I2 is subjected to factory type music which is transmitted by channel I, only local factory amplifiers are turned on for reception of such type music and the local restaurant amplifiers are turned off. However, during the next quarter hour cycle when distribution amplifier I2 is subjected to restaurant type music which is transmitted over channel I, then the local factory amplifiers being automatically turned off, only the local restaurant" amplifiers receive music.

Distribution amplifier I3 is arranged to continuously receive music reproduction from automatic record changers 'I of the hit-parade or measured music type, which is transmitted over telephone line channel #2 to the telephone central station I6, and thence by local subscribers lines I1 to the local "tavern or ice-cream parlor amplifiers I 8. These particular amplifiers are of the coin-controlled type which assure a sufficient time that the patron obtains at least one complete record regardless of the moment the coin is deposited. which approximates about six minutes of music per coin.

In Figure 2 the electrical connections for the distribution console and the automatic record changers 1 are shown with these connections illustrated in heavy lines depicting, for simplicity, coaxial cables while the various control connections are shown in light lines. Also while the automatic record changers for the two channels are illustrated in block diagram, it will be understood that they are sufficient in number to provide the necessary records for a twentyfour hour or shorter preselected period. Consequently, the program may be set once for a twenty-four hour or preselected period and the entire apparatus need mit ter 'further disturbed until thenex't day.' 'In Figure 2 eachfdistrihutin amplifier'l 2and "f3 isillustratedas"provided-'with a'sepa'rate microphone but, ashereinbefore mentioned and as shown in "Figure 1, only a single microphone need be employedwhich `is connected to-either the amplifier |*'2 or-I 3 'by the hand switch fH `Vshown on `the sidel of 'the-microphone (Fig. 41) depending upon the Yparticular'channel overlwhich itis desired-to :make an announcement.

Referring now more specifically to vFigure f3, it willlbe noted ythat power iorfthe equipment lis supplied from the customary domestic sourceof s'u-'pplylof 120 Voltsby conductors-Ll -andii2,which in the actual embodim'entof@the-apparatus is an extension cord plugging in to a wall type recep- -tacleor the like. mainline switch is provided on the console `5 for connecting the equipment to the 'sourcefLI-LZ 'and when soconnecte'd the winding of a f24'fhour clock 26 and the Windfing o'f a l5 minute clock` 2-1 'become energized, with 4this latter clock -21 being Ymounted'on the faceof the automatic'select'or panel, as'shown in Figure 1, for ready observation, since it is this clock which, as hereinbefore mentioned, is synchronized with the v'localamplier clocks yI9. Upon these clocks 26 and 21 being set and started at the correct time the apparatus is then conditioned for operation. Since obviously no centralized music system is customarily operated for a full twenty-four hours, the twenty-four hour clock 26 operates Va cam 28 which maintains a switch 29 in a closed .position for any preselected period of the twenty-four hours depending upon the length of the surface'of cam 28. It has been found that about `sixteen hours operation out of each twenty-four is a-mple to vserve all types of .patrons and 'consequently the cam 28 is designed to close switch v29 for that period of time.

The apparatusthus being conditioned for operation the operator then closes panel switch 30 which illuminates an on signal light 32 and at the same time energizes the primary'winding 33 ofv a transformer-34, `as well as supplying line voltage of 120 volts to the input terminals of a selenium cell rectifier bridge arrangement 35, since an energizing circuit is closed by clock switch 29 and panel yswitch 30. lAtthe same time line voltage is 'supplied `to terminals 36 constituting a socket on the rear of the automatic selector chassis to which the am-pliiiers, turntable chassis 9, and automatic record changers 1 are detachably connected, ior their respective power supply. vIt will also bel noted that Iline voltage is impressed across the plate and indirectly -heated cathode oi a vacuum tube 31 and across'the winding of relay 43 as well as across condenser 38. The lament of vacuum tube 31 is adaptedto be heated from a six volt portion of the secondary windingk 39 of transformer 34 upon operation of ,15 minute clock 21. This latter clock'21 is provided with a cam 4I! arranged to close a switch 42 momentarily every fteen minutes. Upon closure of this switch 42 tube 31 becomes conductive, due to heating of the cathode from a .portion of transformer secondary 39, and current then flows from supply conductor LI through clock switch 29 to the winding of a relay '43, and thence through vacuum Ytube 31, and panel Aswitch 30, back to supply conductor L2 through main vlineswitch 25.

Relay 43 being thus energized attracts its armature 44 with such armature closing a circuit. from one endoi theseconda'ry winding 39, through a conductor :45 to armature 44,"thence by means of a 'conductor 46 to'one end of vthe winding o f a stepper relay 41, and-from the'ther endof relay 'winiingiir tmgraunuiarid 'thus haakte the other end "of transformer 'secondary 3'9lwhich s'l'ipplies-a total voltagefdf approximatelyl3B`-volts. Simul' taneously with energizati'on *c'zhStepper` relay 41, a 'further relay'la is also energized, since one `end of the windingicf vrelayil'` is connected tothe conductor 476 'and the -other 'e'nd to ground, -thus completing faicir'cuit lto `ythe transformerfsecondary winding39. -Inasm'uchlas heating=of thecathofde of 'vacuum tube 31 -islmomentar-y, duetto closure of clock'lswitchllZ,itfollows that the energizatio'n oi relays13,j41 fand24`8f1are-iikewisemomentary.

Thearinature v"49"'o`f relay 341 is vpivotal-ly -eonnecte'd' 'to' "a ratchetrarmSlf-so that "upon energization ofrelay/M fa'njdi attraction off'its `armatlire 49,' thisrratchet` armf50 isr'oc'ked' about itspivo't and momentarily "engages a ratchet gear 52 ro'tating-the latter in a @chuter-clockwise direction, las shown by the' arrow l in# `Figure- 3 against i the bias "O'ft-'coil'Sliiingf'iB- Theift'chet gar52 lis affixed "toi-a shaft-'254 {carrying-Yat its fre'efen'd .an insulated metallic 'contactor 55,"which at 'each `o'perationiof the ratchet gear 52 engages contacts 56, y-of'approximately Vthirty-three -in number, one "at a tune. Thefenerg'izati'o'n of relay "48 'simultaneously with stepper relay 41likewise fca'usesthe armature A5G of 'relay'48 to lbe attracted, which durin'gfits movement rcontacts ahbla'de'fof va'switch 58 tomove the ilatter further in Ia circuit Aopening position. However, following the momentary closure 'of -clockswitch'42 with energization ofrelays f43,'41 and' 48, the filament of vacuum"tub`e31 is `then deene'rgized "rendering "the tube no fflonger con ductive withfth'e result that-the circuit to relay *43 is.thereby'finterrupted. The armature-44 of relay is accordingly released. which interrupts the vcir-- cuit from transformer "secondary 39,1to the windings yoffrelaysf41 andf48 with the *result that their respective armatures`49ra'nd` 51 vare released under the-tension of their customaryrsprings or the like, ready 4for 4theirwnextfcyc'le 'of "operation,

LDuring.movement-of `the armature 51 of relay 48-to its'normal retracted position it again con*- -tacts the bladeof switch-58- causing momentary closure of ythis latter switch. When Vclosed a di'- yrect-or unidirectional-current circuit is `completed iromfthewoutput of -the lselenium cell 'rectify-ing bridge 35, through 'switch 58 to-thewinding of-1a slow-actingdirect'current relay 59, provided with acondenser-ll shunte'd across-its winding. This relay 59-according1y attracts 'its armaturev 62"'for aperiod'of approximately two'seconds before 'release'thereof andcompletes a circuit from oneend of transformer secondary winding 39 through v Iconductor v45, armature 62, aconductor 63 to the metallic 'contacter 55, which is insulated from shaft 54,- and from theparticular contact '55*with -which thecontactor 55 `is at the moment in engagement, through'a conductor "64 v`to a `terminal strip 65 mounted--onthe rear ofthe distribution console, Aandffrorn-the latter by means of control cable 8 (Fig. 1) to a solenoid v(not shown) on the automatic Irecord-changer 1 for selecting a preda- Atermined ygroup of records, Aand from this vlatter solenoid to :ground --a'nd thus back to the remainling endy o-f transformer secondary 39. Accordingly the contactor 55 is advanced `tora new contact I5|'bythe action of re1ays'143 andf'41prior-tore`lay f59 causing Yenergization ofthe solenoidon auto- "matic record changer 1.

VIt can thus be seen that for eachfiifte'en minute period-the `clock721 operates to 'cause rotation 'of the stepper relayj1 41 'with attendantenergization' of 'a solenoid ontheautomatic record changer 1. vWhen* the "latter isenergizedit selects 'a 'group of pre-arranged records which forone fteen minute period may be about four ten inch or three twelve inch records of factory type music for transmission over channel #I and during alternate quarter-hour periods may be approximately the same number of pre-arranged records of restaurant type music. It is also to be noted that while the stepper relay is shown provided with only thirty-three contacts they need not all be utilized if a shorter daily period of music is to be transmitted, and they may be increased in number for a longer daily period, if desired. However, thirty-two contacts will permit a total of eight hours of continuous music over channel #I four hours of which, in intermittent quarter-hour periods, lwill Ibe factory type music with the restaurant type being transmitted for the same period of time. This has been -found to amply service these two types of subscribers, while the hit-parade or measured music is required for a longer daily period accounting for such longer time period being provided by the 24 hour clock 26.

Moreover, as previously mentioned herein the local amplifier clocks I9 are synchronized with the l minute clock 21 on the automatic selector panel so that the local amplier receives only the type of music subscribed for during the quarterhour period when the clock 21 operates the stepper relay to select that particular type music. The additional, or as shown, thirty-third contact is provided for the purpose of resetting the stepper relay for its next daily cycle. Consequently, when the contact arm 55 engages the last contact 56 of the series, and assumingthe slow-acting relay 59 has attracted its armature 62 in the manner as previously described, instead of a circuit now being completed to an automatic record changer solenoid, a circuit will be completed to a return relay 66. This circuit extends from one end of transformer secondary 39 through conductor 45, armature 62 of slow-acting relay 59, conductor 63 to contactor 55then engaging the thirty-third contact 56, thence by means of a conductor B1 to one end of the Winding of relay 66 and from the other end of such winding to ground, thus completing the circuit to the remaining end of transformer secondary 39. Relay 66 accordingly attracts its armatures 68 and 89 and since armature 68 closes a self-holding circuit for relay winding 66 independent of contactor arm 55 movement of the latter will not interrupt the circuit and deenergize relay 66 at the moment. Simultaneously relay armature 59 contacts a detent 'I0 carried by a pawl 12, causing the latter to disengage the ratchet gear 52 and allow the spring 53 to rapidly rotate the contactor 55 in a clockwise direction, until a projecting pin 13 carried by the ratchet gear 52 strikes a stop I4, at which time the contactor 55 will have assumed a neutral position between the iirst contact 56 and the last or thirtythird contact 56, as shown in Figure 3, ready for beginning of the next daily cycle. By the time the pin 13 engages the stop 14, the slow-acting relay 59 will have become deenergized with detraction of its armatureand interruption of the circuit to return relay `fili.

Also carried by the automatic selector chassis are a pair of line matching transformers '15 and 'I6 having 500 ohms primary input and Zero impedance secondary output, with their primary windings connected to the output channels #I and #2 of the distribution amplifiers I2 and I3 as well as emergency amplifier I4, and their respective secondary windings connected to telephone line channels #I and #2. These transformers 'I5 and 'I6 form no operating part of the automatic selector 6 but are carried by the selector chassis solely for convenience and for providing sufficient line matching impedance of the telephone channel lines.

The next unit in the distribution console is the turn-table chassis 9 as previously mentioned, which like all the console units is readily detachable so as to be removed therefrom Whenever desired. This unit is provided for the presentation of dedication music only upon request and under normal conditions it is not operated but certain circuits oi' the apparatus pass through such unit. By reference now more particularly to Figure 4, it will be noted that a pair of supply terminals 89 are provided on the turn-table chassis which connect to the terminals 36 (Fig. 3) on the automatic selector chassis 6. A conductor 82 connects one of these supply terminals to one end of the winding of a relay 83, to one side of the turn-table motor 84, and to one end of the winding of a further relay 85. The remaining supply terminal 8i? is adapted to be connected by a conductor 96 to the remaining ends of the respective relays 99 and 85, as well as to the other side of the turn-table motor 84, upon closure oi. a turn-table automatic on and off switch 8l. Thus in the normal condition of the turntable unit none of these elements are energized and the armature 88 of relay 85 completes a circuit from a turn-table chassis terminal 89, connected by one of the conductors I5 (Fig. 2) extending frorn the automatic record changer 'I for l, channel #5, and to a further turn--table chassis terminal 99, which latter is connected by a conductor 9'?. to the input of the distribution amplifier I2 for channel #I with this conductor 92 also extending to the input for emergency stand-by amplifier I4, as indicated by the legend in Fig ure 4.

The turn-table chassis is also provided with a further pair of terminals 93, connected by the conductors 8 (Fig. 2) extending from a 11'1 volt A. supply of the automatic record changer These terminals 93 are in turn connected to a further pair of turn-table chassis terminals 94 by the armatures 95 and 96 of relay 83 in the deenergized position of the latter, with such terminals Srl being connected by conductors 91 and 98 to a relay 99 provided on the distribution amplier l2 (Fig, 4). When, however, a dedication request is made the selected record is placed on the turn-table of chassis 9 and upon movement of the pick-up arm i90, the automatic switch 91 moves to the on position. This closes the circuit from the supply terminals to the windings of relays 83 and 85 as well as to the turnmtable motor 84 causing the latter to rotate the selected record. At the same time relay armature 89 is attracted interrupting the channel #i music -from the automatic record changer 1 and connecting the pick-up arm IGI] to the input of distribution amplifier I2 and emergency ampler I 4 through terminal 90 and conductor 92. Likewise the armatures and 95 interrupt the 117 volt A. C. from the automatic record changer, which is connected to the turn-table chassis terminals 93, and connect the distribution amplifier relay 99 to the supply terminals Gil of the turn-table chassis 9, through conductors 82 and 85, automatic switch 91, chassis terminals 95, and conductors 91 and 98. The dedication music is thus transmitted from the requested record on turn-table 9 gf through. channel# hand uponpcompletion oflsuch record the-pick11parm llliautomatically opens switch 81, deenergizing` the motor 84 together with relays 83 and 85,.and immediately restoring the channel.#| Vmusic directlyfrom the automatic recordVK changer `1.

As shown .inFigure 4 tl'ievarious circuits within4 amplifier chassis |2 are shown with theinput thereto constituting the conductor 02 extending to-an L-typevolume control for the-channel #'I music' (operablefrom the panel front), one end of which is groundedand thus connected to the other grounded conductor of the coaxial cable f which conductor 92 is composed. yFrom the remaining portion of volume control |02, the signalpasses through a first amplifying stage repre- 'sented byv thetube|03 and its associated customary resistors into a second.y amplifying stage comprising a tube |04 andthence through a last st-age'includingV two' vacuum tubes |05 and |05 to` the primary of 1 theusual output transformer |01. Since the'amplifying circuit, includingv the above mentioned. tubes and associated elements is well known in theart, it is believedunnecessary toy specifically tracel the path of current flow through thexamplify'ing stages Ifollowing the input signal impressed on Volume control |02` It Will befn'ote'd; however,` that the amplifier chassis |2i is provided with an auxiliary amplifying stage consisting of a-tube |00' and associated elements which during normal operationl of ampliiier |2 isv ineffective due to` thegrounding of the grid and plate ofvtube: |fr through resistors |09 and ||0` and an armatureV ||2' of a relay ||3 Moreover, a resistor ||4 is provided which is connected togroundby armature |:|2 and tothe plate circuit lof tube' |04, with suchresistor ||4 being of sunicient ohmic value toy prevent too greata load on theI amplifier output whiler the auxiliary stage is -grounded andra-t the same. time this resistor ||4is small enough in value so as not to effect the plate voltage on the auxiliary stagewhen rendered operative, as hereinafter mentioned.

Also carried by ampliiier chassis |'2 is a power transformer ||f5 havingitsprimary winding con-- nected to the power supply from the automatic selector B comprising the terminals 3S of Figure 3. The secondary Winding of transformer H5 is shown as constituting two low voltage windings ||5`r andI |f|1 anda higher voltage winding Htl; Winding |'I6 supplies heating current to the' series 4connected lamentary cathodes of a pairl of reotifying tubes H3 while low voltage winding ||1 energizes relay I I3 upon closure of al pushbutton-switch on thel front panel of distribution amplifier I2' Whenit is desired to make a public announcenent over channel #l it is-customarily done during the intermission period between quarterhour program changes, which approximates ve minute intervals, Vand during-which intermission relay 99 is deenergized by interruption'fof its 117 volt supply at the automaticrecord changer 1`. Panel switch l'20is accordingly closed energizing relay ||3 withv attraction 'of its armature H2; thus removing the ground connection from the vgrid and plate of thel auxiliary stage including tube irend'ering such stage operable, and the announcer speaks into microphone |0 (having previously perated microphone switch to select distribution 'amplifier i2 in this instance). The signal then passesV through microphone outlput volumeV control I'l and all amplifying stages to Output tiaisf'rii IUTf'and f'rn th-secondary winding |22; thereof, through therlow path lter circuit, comprising choke coils |23 and |24 as well. as condenser-|25, whichv limits the highest outputA frequency to a definite frequency as required bylocal telephone company requirements, and thenl through output coaxial cable |26, as'noted by thelegend, to the; primary winding ofline matching transformer 16 on'the automatic selectorchassis 6,- (Fig. 3) andffrom the secondary winding thereof overtelephone line channel til` to the localamplifiers I8 (Fig. 1). Upon completion.- of the announcement switch |20 isl again-opened deenergizing relay ||3 thus restoring the grounchconnection for the auxiliary stage and conditioning the distribution amplifier I2- for continuation of; the musical program from the automaticrecord changer-1 through input conductor 92.

Although, as abovestated, public announcements are customarily made during the intermissionv period, so as -to prevent interruption of the musical program,` in case of an emergency an announcement can be made at any time. Should such necessityarise thev operator need only adjust the musicV volume control |02 to its lowest level andslightly raise the. volume control for microphone I0 which enables the voice announcement to be superimposedl on the musical program without distortion due to the Very4 low volume of the'latterduring any such emergency announcement.

As shown in Figure 4, the amplifier I2 is provided with al monitor comprising a speaker |21 and a D. C. meter |28. This speaker |21- is connected to taps on-y the secondary winding |22 of output transformer |01 throughl a balancing L-shape volume control |129- and an additional armaturefor contact |30- of relay'||3, Meter |28 is connected in parallel with speaker l2l'through a selenium cellfrectier |532 and an adjustable resistance |33. Thus the operatorV is able to monitor the system at all times since the program is received by the monitor speaker |21 at the distribution amplifierV |2 and current conditions ofk the circuit` are continuously indicated by themeter |28; It will be noted, however, that anyfannouncement'made over microphone E0 is not picked up by the monitor speaker |21 because the circuit to the latter is interrupted by armatureA |30 of relay ||3 which operates simultaneously Witharmature ||2 of this same relay |13, and thus a ifa-broadcast from monitor speaker |'21 over microphone I0 is prevented during the making of -an announcement.

In order to maintain the transmitted music at a constant tone level regardless. of amplitude variations between diierent records, the distribution ampliiier I2 isprovided with a tone level equalizer. As shown in Figure 4 such equalizer comprises a resistor |34 connected in series with a 6 watt incandescent lamp |35 across the secondary winding |22 or output transformer |01. A further resistor |36 is connected in series with resistor |34, andv hence to the output circuit comprising secondary Winding |22, and to the cathode electrode of the first stage amplifying tube |03, to produce a negative feed-back. As'the output from winding |22 increases, lamp |35 lights and increases the resistance of the circuits. Such resistance increase causes an inverse'variation in the voltage, reducing the overall gain of the entire amplifier system, and resulting in stabilization'of the amplitude oi the signal, with attendant transmission of the zreproduce'd music at a constant tone level regardless of variations between different records.

If for any reason the distribution amplifier I2 should fail this would normally mean an interruption of transmission until the trouble is corrected. To eliminate such contingency an einergency amplifier I4 is provided in accordance with the present invention which, as hereinbefore stated, immediately takes over the transmission of the program without interruption. In order to fire the emergency amplifier I4 by making the latter instantaneously operative in the event of trouble in ampliiier I2, the rectified energy from rectiiiers ||9 is supplied to the plate and screen grid of the last amplifying stage tubes |05 and |05 through a nlter circuit, comprising a resistor |31 and condensers |38, and a resistor |39 shunted across the winding of a relay |40.

Since relay 99, as previously mentioned, remains energized as long as a program is being transmitted from automatic record changer i, or a dedication record from turn-table chassis 9, the armature of relay 99 will remain attracted which completes the rectifying circuit through rectifiers 9 back to the center tap of the secondary winding IIS of transformer M5 through a series connected amplifier on lamp |4I. However, since an announcement is customarily made over the microphone Ill during an intermission at which time relay 99 is deenergized, it is necessary that the rectifying circuit be completed by some other means than armature of relay 99. To this end the armature I I2 of relay |I3 then operates to -connect the midpoint of the secondary winding of transformer ||5 to ground, upon energization of relay |I3 by closure of switch |20 as before mentioned.

Under normal operating conditions resistor |39 in the load circuit of rectiiiers ||9 limits the voltage across relay |40 to a value insuiiicient to cause energizaticn thereof and also the voltage supplied to the plate and screen of tubes |05 and |06 is such as to have no effect on their operation. Should trouble develop in the power transformer II5 or the rectifying circuit including the rectifiers |I9 causing disruption of power supply fuse |42, the power will then be supplied to the emergency amplifier ring terminals |43, one side by a conductor |44 to a normally closed contact with an armature |45 of relay |40 and thence by a conductor |45 to one of the chassis terminals |43, while the other side of the supply source extends through the primary winding of power transformer H5 (now carrying no current). through a conductor |41 to a normally closed contact with a further armature |48 of relay |40, and thence by a conductor I 49 to the other chassis terminal I 43, which thus supplies a firing voltage to emergency amplifier I4 to cause operation thereof as hereinafter explained.

At the same time trouble lamp |50 will show a red. signal on the panel of distribution ampliiier I2 since such lamp is then connected across the supply source comprising the conductors |44 and |41 indicating trouble in the amplier I2. At the same time the interruption of a voltage from rectiiiers ||9 to the plate and screen of last amplifying stage tubes |05 and |06 renders them non-conductive so that the signal is no longer transmitted through output transformer |01. On the other hand should trouble develop in the amplifying stages, such as the burning out or short circuiting of a tube, a condenser, or a resistor; orshould any element draw more than normal current, then the voltage drop across resistor |39 will increase because of the influence on tubes 05 and |06 of an abnormal condition. This increase in voltage drop across resistor i3d causes an increase in the Voltage across shunt connected relay |40 with attendant energiaation thereof and attraction of its armatures i453 and |48 `and at the same time tubes It and |03 become inoperative to further transmit the signal to output transformer |01.

Upon attraction of armatures |45 and |48 a firing voltage is again supplied to the chassis terminals i143 since one side of the supply source again extends through conductor |44 and to a contact with which the attracted armature |45 is now in engagement, and thence again by conductor |46 to one of the chassis terminals |43. The other side of the supply source now extends through a conductor I 52 to a contact with which the relay armature |48 is at the moment in engagement, and thence again by conductor I 49 to the remaining chassis terminal |43. It will thus be seen that a voltage is supplied to the firing terminals |43 upon failure occurring in any of the amplifier stages, or disruption of the power fuse I 42, which automatically causes the emergency amplifier I 4 to instantaneously become operative as will be later described.

By reference now more particularly to Figure 5, it will be obvious to those skilled in the art that the distribution amplifier I3 for channel #2, and which transmits measured music continuously, is identical in all respects to distribution amplifier I2 and hence like elements bear the same reference characters. For this reason the complete electrical circuit for the various amplifying stages has not been repeated in the showing of the amplifier I3 in Figure 5. Instead the amplifier I3 is schematically shown with numerous plug-in type sockets |53 for the reception of containers |54, such as shown in Figure 7, which are provided with radio type bases |55. These containers |54 house various resistors and capacitors, as can be seen from Figure 6, which are elements most commonly subject to wear and need replacement from time to time. By placing such elements in containers |54, it is unnecessary for maintenance men to be highly skilled in order to service the equipment. In the event of trouble the service-man merely removes the various containers, each of which have a type designation, and replaces with new containers until the trouble is corrected. The defective container is then returned to the factory or main service center Where it is opened and tested, after which the required new element is installed and the container resealed for another installation. As an example, the elements diagrammatically shown in Figure 6 as being housed in the container |54 of Figure 7, are also shown in dotted line in the distribution amplifier Ii. of Figure 4.

inasmuch as distribution amplifier I3 is employed entirely for continuous measured music. it has no connection to the turn-table 9 and instead the I|1 volt supply foi` relay 39 of amplifier |3 is supplied directly from automatic record changer 1 through conductors 8 (Fig. 2). Likewise the coaxial input cable I5 (Fig. 2), and as indicated by the legend To automatic record changer channel #2 of Figure 5, extends directly from the automatic record changer 1 for channel #2, to the input chassis terminal |56 for distribution amplier I3 and to the emergency ampliiier input chassis terminal |51 for channel #2. The input conductor 92 of distribution amplifier I2 also isl connected to an emergency amplifierinput chassis terminal |58 as previously mentioned. The output terminal |59 of distribution amplifier I3 is connected by a coaxial cable or the like to the primary winding of line matching transformer 15 on the automatic selector chassis 6 and from the secondary Winding thereof over telephone line channel #2 to the local amplifiers IBlFig. l), in the same manner as previously described relative to the output of distribution amplifier I2 for channel #L Also distribution amplifier I3 is provided with the same arrangement for firing the emergency amplifier I4 which, as previously mentioned, is identical to that of amplifier I2.

Figure 5' also shows the emergency amplifier I4 which so far as the various amplifying stages are concerned is also identical to distribution amplifiers I2 and I3, with few exceptions. For example, the emergency amplifier. is naturally not provided with an auxiliary stage for public announcements since such would be superliuous, nor is it provided with the various relays 99,' II3 and |40 which operate in conjunction with the making of an announcement and the firing of the emergency amplifier I4, but in practicallyall other respects the amplifying stages of emergency amplifier I4, shown to the-left of the dot-dashed line Eof Figure 5, are identical to amplifiers I2 and4 I3 as indicated by the use of the same reference characters. Consequently, the output from the various .amplifying stages of emergency amplifier I4 may be considered for purposes of explanation as a terminal |60, and a detailed description only of the circuits which automatically cause operation of the amplifier I4 in re'. sponse to firing by the defective distribution amplifier I2 or I3 should suffice, as all other phases of operation should be clear from the foregoing description of the distribution amplifiers I2 and I3.

Accordingly, it will be seen thatv emergency amplifier I4 issupplied with power from the automatic selector chassis terminals 36 which is also connected by conductors |62 and |63 to the input side of a reetox` or selenium cell rectifier bridge arrangement |64. The D. C. or unidirectional current output from this bridge arrangement is connected by a conductor |65 to one side of the winding of two relays' |66 and |61 while the other negative side of the bridge |64 is connected by a conductor |68 and normally closed switch |59 to the cathode electrode of a pair of gaseous discharge tubes and |12 having a critical voltage breakdown characteristic. The

remaining ends of the winding of each of the relays |66 and |61 are connected to the anode or plate of the discharge tubes |10 and |12, respectively.

The cathode and starting electrode of tube |10 is connected to the secondary winding of a transformer |13, the primary winding of which is connected to the firing terminals |43 of dis'- tribution amplifier I3 and in a similar manner the cathode and starting electrode of tube |12 is connected to the secondary winding of a trans-- former |14 likewise having its primary winding connected to the firing terminals |43l of distiibution amplifier I2. Thus, upon closure ofthe firing circuit from distribution amplifier I2 or I3, due to the occurrence of a defect therein as previously described, transformer |13 becomes energized in the case of failure of distribution amplifier I3 andtransformer |10 becomesenergized in case of failure of distribution amplifier Upon energization of transformer. |13 or x |141 the:V secondary winding; thereof irripresses. a voltage acrossy the starting electrode and cath ode of discharge tube |10 or |12 as the case may?` be'.` Such voltageis suflicient to cause ionization of the gaseous medium within the tube which then vinitiates a discharge between the cathode andplateof thetube thus completing a circuit to. the respective relayl |66 or |61'with whichthe particular tube` isconnected.

Assuming that distribution amplifier I2 has failed with operation of its firing circuit and relay |6.1- has thus become energized the latter will attractitsarmature |15. A circuit is then completed from oneend of low voltage winding II1 ofr power transformer II5, through a con'- ductor |16 to a junction |11, thence from this junction by aconductor |18 lto engagement with attractedarmature |15, a conductor |19 to one end of a winding ofa pair of relays |80 andf |82, and from the remaining end of the lrespective re.-

conductor |84 tothe opposite end of secondary winding |I1. Bothrelays |80 and IB-Zare ac` cordinglyy energized with attraction of their respective armatures. Armature |85 of relay |82 completes a connection from the input chassis terminal |5B=from ampl-ier I2v carrying channel #l mus-ic, through a conductor N-and attracted armature |85: to a junction |81 and thenceffrom this junction by means of a conductor |88 to emergency amplifier inputyolume control |02. The signal-from automatic record changer 1l or turntable 9' whichwas passing through distribution amplifier IZatthef time it became defective is'thus automatically andA substantiallyy instantaneously` transferred to. emergency amplifier stages and tothe output terminal' |60 thereof.

ISince relayY |80 was .energized simultaneously with relay |82 itsarmatures` |89 andr |90 are likewise attracted. A connection from amplifier stageoutput terminal' |60 is thus completed to the low pathfil'ter circuit, comprisingthe-chcke coils |23andv |24as wellfas condenser |25, of disu tribution amplifier I2, whichv extends from-.ten minal |60 through a conductor |92 to armature |89, then by a conductor |93 to an emergency chassis terminal |94 and thence byv a conductor |95. to a junction |961* (Fig. 4) with the low path fil-ter circuit asy above mentioned. Hence distribution.y chassis |2- upon becomingdefective is completely by-passed except for the low path filterl circuitk with the signal passing through emergency amplifier 4.

Closure of armature |9|lA of relay |80 merely completes a circuit from the midpoint of power transformersecondary IIB, by means of a conductor |91,A armature. |90,` a conductor |98,A and junction |9191,- to an vemergency amplifier on lampv 200 and to ground, which lamp is illu-'- minated`- substantially simultaneously with. the red trouble lamp |V ofi-distribution amplifierI I2", thus indicating tothe operator that amplifier I2 has become defective and emergency amplifier |.41has taken-zover. When the trouble causing the .failure of amplifier I2 has been correctedA the operator then merely momentarily opens emergencyA amplifier switch |69. This deenergizes relay |61 which in turn deenergizes relays |80 and |82: with detraction of their respective armatures: thus opening all circuits and rendering the emergency amplifierA no longer operative so long as the trouble hasbeen rectified. If, however,

such is: not the case,.the immediate reclosure of switch I69fwould` immediately causeca repetition ,Sofay the c-ycl'e of-...'operation, as above described,

15 should transformer |14 still be energized due to closure of the firing circuit of distribution amplifier l2.

If it be now assumed that distribution amplifier |3 falls with closure of its firing circuit, then transformer |13 becomes energized. This causes breakdown of tube |10 with attendant energization of relay |66, in the same manner as previously described relative to relay |61. Attraction of armature 202 of relay |61 causes energization of a pair of relays 203 and 204 since the windings theerof are then connected to the junctions |11 and |83 which as previously explained correspond to the transformer Winding ||1. Attraction of armature 205 of relay 204 connects the input chassis terminal |51 for channel #2 music, by means of a conductor 206, armature 205, conductor 201, junction |81 and conductor |88, to the input volume control |02 of emergency amplifier I4. Attraction of armatures 208 and 209 perform the same operation as the armatures |90 and |89, respectively, of relay |80. That is to say, armature 209 completes a circuit from the midpoint of secondary winding ||8 by means of conductor |91, armature 209 and a conductor 2|0 to the junction |99 and hence to emergency amplifier on lamp 200. Relay armature 200 in this instance connects the amplifier stage terminal |60 to an output chassis terminal 2|2 which is connected by a coaxial cable 2| 3 to a junction 2| 4 (Fig. in the loW path filter circuit comprising the choke coils |23 and |24 as well as the condenser |25 of distribution amplifier I3. Again it will be seen that upon failure of distribution arnpliier I3 the latter is completely by-passed except for the low path filter thereof with the emergency amplifier instantaneously taking over the continuous measured music of channel #2 until the difficulty with distribution amplifier I3 is corrected at which time the apparatus is restored to normal by momentarily opening emergency amplier switch |09 as above described.

It thus becomes obvious to those skilled in the art that a centralized music system is herein provided in which musical programs of three distinct types are transmitted to local subscribers over only two telephone line channels thereby eliminating considerable costly equipment heretofore required and greatly decreasing operating expense. Moreover, only a single distribution console is required which is provided with an automatic selector chassis and which is automatically operable at predetermined periods of time to select the appropriate program transmitted to synchronized local subscriber stations. The distribution console also has a phonographic turntable chassis for request dedication programs as Well as distribution amplifier chassis for each telephone line channel with each amplifier chassis being automatically operable to maintain a constant tone level regardless of amplitude variations in the reproduced music. Coupled with each distribution amplifier is provision for the making of public announcements Whenever desired to the local subscriber or patron stations. An emergency stand-by amplifier chassis also carried by the distribution console automatically and instantaneously takes over amplification of the reproduced music upon failure of either of the distribution amplifiers for the telephone line channels. Furthermore, the entire equipment is designed to maintain servicing at a minimum and by providing easily detachable sealed containers housing most of the elements subject to ,wear and deterioration, the services of skilled mechanics is not required enabling the equipment to be maintained in efficient operating condition by the average laymen. Also, since the automatic record changers are entirely independent oi the distribution console, they need not necessarily be purchased unless the number of prospective subscribers fully warrants, as the distribution console can be connected to an existing studio in an adjacent city or town, from Whom the reproduced music may be rented.

It is also to be understood that While the present invention primarily contemplates the distribution of the three types of programs mentioned, any given distributor may dispense With the measured or juke-box type should they so desire and in lieu thereof utilize channel #2 for alternate programs of the restaurant and factory types, in the same manner as herein described relative to channel #L or in fact utilize simultaneously both channels for the same programs. In such an instance of course all local amplifiers would accordingly be of the Synchronized clock control type since coin-controlled local amplifiers would not be required and in fact would be a detriment under such circumstances.

Although one embodiment of the present invention has been shown and described it is to be understood that still further modifications thereof may be made Without departing from the spirit and scope of the appended claims.

I claim:

1. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music of different types at preselected intervals, an automatic record changer connected to said automatic selector and operable to reproduce the prearranged program of the type as selected by said automatic selector, a distribution amplifier carried by said console and conected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single telephone line channel to local subscriber stations, an emergency amplifier carried by said console and connected 'to said distribution ampliner and adapted to automatically and instantaneously operate upon failure of said distribution amplifier to amplfy and distribute the reproduced music at the moment supplied by said automatic record changer to said distribution amplifier, and means comprising a ring arrangement forming part of said distribution amplifier and connected to said emergency amplifier for operating the latter upon failure of said distribution amplifier for any reason.

2. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music of different types at preselected intervals, a remotely located automatic record changer ccnnected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, a distribution amplifier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single telephone line channel to local subscriber stations, a second distribution amplifier carried by said console and connected to said automatic record changer for amplifying and distributing reproduced music of a still further type from the latter continuously over a second telephone line channel to additional local subscriber stations of the coin-controlledA type, an emergency amplifier carried by said console and connected to both of said distribution ampliers and adapted to automatically and instantaneously operate upon failure of either of said distribution amplifiers to amplify and distribute the reproduced music at the moment supplied by said automatic record changer to the respective failed distribution am-u plifier, and means comprising a iiring arrangement forming part of each respective distribution amplifier and connected to said emergency amplier for operating the latter upon failure of either of said distribution ampliers for any reason.

3. A music reproduction system comprising a distribution console provided With an automatic selector for selecting pre-arranged program music of diierent types at preselected intervals, a remotely located automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, a distribution ampliiier carried by said console and connected to said automatic record changer :for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single telephone line channel, a plurality oi local sub-- scriber stations connectedto said single telephone line channel and provided with means synchronized with said automatic selector to cause some of said local stations to receive reproduced music oi only one type and other of said local stations to receive reproduced music of only another type for respective time intervals as selected by said synchronized automatic selector, a second distribution amplier carried by said console and connected to said automatic record changer for amplifying and distributing music of a still further type from the latter continuously over a second telephone line channel, a plurality of local subscriber stations of the coin-controlled type connected to said second telephone line channel for the reception of the continuously reproduced music for periods of time determined by the number or denomination of the coins deposited in said local coin-controlled station, an emergency amplier carried by said console and connected to both of said distribution ampliers and adapted to automatically and instantaneously operate upon failure of either of said distribution ampliiiers to amplify and distribute the reproduced music at the moment supplied by said automatic record changer to the respective failed distribution amplifier, and means comprising a ring arrangement forming part of each respective dis-- tribution amplifier and connected to said emergency amplifier for operating the latter upon railure of either 4of said distribution ampliiiers for any reason.

4. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music of diierent types at preselected intervals, a remotely located automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said Vautomatic Selector, a distribution amplier carried by said console and connected to said automatic record changer vfor amplifying and distributing the reproduced music from the Vlatter land of the type selected at any rmoment by said automatic selector over a single telephone line channel to local subscriber stations, a second distribution amplier carried by said console and connected to said automatic record changer for amplifying and distributing reproduced music of a still further type from the latter continuously over a second telephone line channel to additional local subscriber stations of the coin-controlled type, and a microphone adapted to be connected at the will of an bperator to either of said distribution amplifiers for making public announcements to local subscriber stations.

5. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music of diirerent types at preselected intervals, a remotely located automatic record. changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, a turntable chassis carried by said console and operable to interrupt the reproduced music from said automatic record changer and to reproduce requested program music when desired, a distribution amplifier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector or the requested program music `from said console turntable over a single telephone line channel to local subscriber stations, a second distribution ampliiier carried by said console and connected to said automatic record changer lor amplifying and distributing reproduced music of a still further type from the latter continuously oyer a second telephone line channel to. additional local subscriber sta- 610115, Of the soiufcpntrQl-ld type, and a microphone adapted to be connected at the will of an operator t0 either Of Said ,distribution amplifiers for making public announcements to local subscriber stations.

6- A musi@ 'lPrQquton SYStem Comprising a distribution console provided with an automatic selector for selecting pre-arranged program music of different types at preselected intervals, a remotely located automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, a distribution ampliier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of .the type selected at any moment byL said automatic selector over a single telephone line channel to local subscriber stations, and said distribution ampliiier including a container housing various electrical elements normally subject to deterioration and provided with a base detachably engageable with a socket to facilitate removal `and insertion of said electrical elements in gir uit with the customary electronic tubes of said distribution amplifier.

7. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music oi different types at preselected intervals, a remotely located automatic record changer connected to said automatic selector and operablel -to reproduce the pre-arranged program of the type as selected by said automatic selector, a turn-table chassis lcarried by said console and operable to interrupt the reproduced music from said autornauiic record changer and to produce requested DrQgIm music when desired, a distribution amplier carried by said console and connected to said automatic record changer through said turn-table chassis for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector or the requested program music from said console turn-table over a single telephone line channel, a plurality of local subscriber stations connected to said single telephone line channel and provided With means synircnized With said automatic selector to cause some of said local stations to receive reproduced music of only one type and other of said local stations to receive reproduced music of only another type ior respective time intervals as selected by said synchronized automatic selector or to receive the requested program music from said console turn-table depending upon the time interval during which the requested program music is reproduced, a second distribution ampliiier carried by said console and connected to said automatic record changer for amplifying and distributing music of a still further type from the latter co-ntinuously over a second telephone line' channel, a plurality of local subscriber stations of the coin-controlled type connected to said second telephone line channel for the reception of the continuously reproduced music for periods of time determined by the number or denomination of the coins deposited in said local coin-controlled station, an emergency amplifier carried by said console and connected to both of said distribution amplifiers and adapted to automatically and instantaneously -operate upon failure of either of said distribution ampliiiers to amplify and distribute the reproduced program at the moment supplied by said automatic record changer or the console turn-table to the respective failed distribution amplifier, means comprising a iiring arrangement included in each respectivey distribution ampliner and connected to said emergency ampliiier for operating the latter upon failure of either of said distribution ampliiiers ior any reason, and a microphone adapted to be connected at the will of an operator to either oi said distribution ampliiiers for making public announcements.

8. A music reproduction system comprising a distribution console provided with an automatic selector for selecting pre-arranged program music ci diierent types at preselected intervals, a remotely located automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, said automatic selector including a synchronous electric clock operable to periodically close an electric circuit and a stepper relay intermittently operable upon closure of said electrical circuit to cause operation of said automatic record changer, and a distribution amplier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single telephone line channel to local subscriber stations.

9. A device for a distribution amplifier chassis comprising a container housing various electrical elements operable in conjunction with an electronic amplifying tube when subjected to a signal, and a base secured to said container and engageable with a socket on said chassis to facilitate removal and insertion of the electrical elements as a unit 'from the customary electrical 20 circuit of said distribution ampliiier including said electronic amplifying tube.

10. A music reproduction system comprising a distribution console provided with an automatic selector having means comprising a time clock for selecting a pre-arranged music program for periods of time as established by said time-clock, an automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program from a plurality of previously arranged records, a distribution ampliiier detachably carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter as selected at the moment by said automatic selector to local speakers, and means connectable at the will of an operator to said distribution amplier for the transmission of a special dedication program or the making of a public announcement over the music transmission system to local speakers.

l1. A music transmission system comprising a distribution console provided with an automatic selector having means comprising an electrically synchronous time clock for selecting a pre-arranged program at preselected intervals or a continuous pre-arranged musical program for time periods as established by said synchronous timeclock, an automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program from a plurality of previously arranged records, a distribution amplier detachably carried by said console and connected to said automatic record changer for ampliiying and distributing the reproduced music from the latter as selected at the moment by said automatic selector to local speakers, means independent of said automatic record changer and connectable at the will oan operator to said distribution amplier for transmitting a different program over said system, and a microphone connectable at the Will of an operator to said distribution amplifier for the making of a public announcement over said transmission system when desired.

12. A music reproduction system comprising a distribution console provided with an automatic selector, music reproducing means connected to said automatic selector and operable to reproduce musical programs of at least two different types, a distribution amplifier carried by said console and connected to said music reproducing means for amplifying and distributing the reproduced music from the latter over a single pair of conductors to local speakers, and said automatic selector including means comprising a synchronous electric time-clock operable at predetermined intervals to alternately select one or the other of said types of musical programs for transmission to said local speakers.

13. A music reproduction system comprising distribution console provided with an automatic selector having means comprising a synchronous electric time-clock for selecting a music program of at least tWo different types of music, an automatic record changer connected to said automatic selector and operable to reproduce a pre-arranged program of one type or another from a plurality of previously arranged records, and a distribution amplier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type as selected at the moment by said automatic selector and for a denite period of time as determined by said 21 time-clock, over a single pair of conductors to local speakers.

14. A music reproduction system comprising a distribution console provided with an automatic selector having means comprising an electrically synchronous time-clock for selecting pre-arranged program music of different types at preselected intervals as established by said synchronous clock, an automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector, a distribution amplifier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single pair of conductors, and a plurality of local speaker stations connected to said single pair of conductors and provided with an electric time-clock synchronized with the synchronous electric clock of said automatic selector to cause some of said local speaker stations to receive reproduced music of only one type and other of said local speaker stations to receive reproduced music of only another type for respective time intervals as selected by the synchronous time-clock of said automatic selector and by the synchronized electric time-clock at the local speaker stations.

15. A music reproduction system comprising a distribution console provided with an automatic selector having means comprising a time-clock 22 for selecting one or the other of a pre-arranged` music program for periods of time as established by said time-clock, an automatic record changer connected to said automatic selector and operable to reproduce the pre-arranged program of the type as selected by said automatic selector in conjunction with its time-clock, a distribution amplifier carried by said console and connected to said automatic record changer for amplifying and distributing the reproduced music from the latter and of the type selected at any moment by said automatic selector over a single pair of lines to local speaker stations, and said distribution amplifier being provided with an automatic tone level equalizer for maintaining the reproduced music received by the local speaker stations at a constant tone level regardless of tone variations between different records.

SAMUEL K. LACKOFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,230,486 Durant Feb. 4, 1941 2,238,976 Hadel et al. Apr. 22, 1941 2,241,663 Hayslett et al May 13, 1941 2,242,197 West et al May 13, 1941 2,306,654 Treman Dec. 29, 1942 2,396,756 Snodgrass Mar. 19, 1946 

